Next generation communication systems are being developed in order to provide various high-speed large-capacity services to Mobile Stations (MSs), and are making use of the OFDM or OFDMA scheme into consideration. Hereinafter, structures of a signal transmission apparatus and a signal reception apparatus of a conventional OFDM or OFDMA communication system will be described with reference to FIGS. 1 and 2.
FIG. 1 is a block diagram illustrating a structure of a signal transmission apparatus of a conventional OFDM/OFDMA communication system.
Referring to FIG. 1, the signal transmission apparatus includes an encoder 101, a modulator 103, a serial-to-parallel (S/P) converter 105, an Inverse Fast Fourier Transform (IFFT) unit 107, a parallel-to-serial converter 108, a Cyclic Prefix (CP) inserter 109, and a Radio Frequency (RF) processor 111.
First, when a signal to be transmitted occurs in the signal transmission apparatus, the signal is input to the encoder 101. The encoder 101 encodes the input signal according to a preset encoding scheme and then outputs the encoded signal to the modulator 103. The preset encoding scheme may be, for example, a turbo encoding scheme or a convolutional encoding scheme. The modulator 103 receives the signal output from the encoder 101, modulates the signal according to a preset modulation scheme, and then outputs the modulated signal to the S/P converter 105. The preset modulation scheme may be, for example, a Quadrature Amplitude Modulation (QAM) scheme, a Binary Phase Shift Key (BPSK) scheme, or a Quadrature Phase Shift Keying (QPSK) scheme.
The S/P converter 105 receives the serial signal output from the modulator 103, converts the serial signal to parallel signals, and then outputs the converted parallel signals to the IFFT unit 107. The IFFT unit 107 receives the parallel signals output from the S/P converter 105, performs IFFT on the parallel signals, and then outputs the IFFTed signals to the P/S converter 108. The P/S converter 108 converts the parallel signals output from the IFFT unit 107 to a serial signal, and then outputs the converted serial signal to the CP inserter 109. The CP inserter 109 inserts a CP to the serial signal output from the P/S converter 108 and then outputs the CP-inserted signal to the RF processor 111. The RF processor 111 receives the signal output from the CP inserter 109, performs RF processing of the signal, and then transmits the RF-processed signal through an antenna.
FIG. 2 is a block diagram illustrating a structure of a signal reception apparatus of a conventional OFDM and OFDMA communication system.
Referring to FIG. 2, the signal reception apparatus includes an RF processor 201, a CP remover 203, an S/P converter 204, a Fast Fourier Transform (FFT) unit 205, a P/S converter 207, a demodulator 209, and a decoder 211.
The RF processor 201 receives an RF signal from a signal transmission apparatus, restores an original signal before the RF processing from the received RF signal, and outputs the restored signal to the CP remover 203. The CP remover 203 receives the signal output from the RF processor 201, removes the CP from the signal, and then outputs the CP-removed signal to the S/P converter 204. The S/P converter 204 receives the serial signal output from the CP remover 203, converts the serial signal to parallel signals, and outputs the parallel signals to the FFT unit 205. The FFT unit 205 receives the parallel signals output from the S/P converter 204, performs FFT on the signals, and then outputs the FFTed signals to the P/S converter 207. The P/S converter 207 receives the parallel signals output from the FFT unit 205, converts them into a serial signal, and then outputs the converted serial signal to the demodulator 209. The demodulator 209 demodulates the signal output from the P/S converter 207 according to a demodulation scheme corresponding to a modulation scheme used in a signal transmission apparatus corresponding to the signal reception apparatus, and outputs the demodulated signal to the decoder 211. The decoder 211 decodes the signal output from the demodulator 209 according to a decoding scheme corresponding to an encoding scheme used in the signal transmission apparatus corresponding to the signal reception apparatus, and outputs the decoded signal.
Meanwhile, in order to provide various types of services, next generation communication systems are being developed in pursuit of broadband communication systems capable of providing a broadband service. Current broadband communication systems that have been proposed up to now are systems designed based on a basic assumption that broadband communication systems are allocated different frequency bands for providing the broadband service, respectively. In order to provide the broadband service through different frequency bands, each frequency band requires a signal transmission apparatus as shown in FIG. 1 and a signal reception apparatus as shown in FIG. 2, that is, as many signal transmission apparatuses of FIG. 1 and as many signal reception apparatuses of FIG. 2 as the number of used frequency bands are required, respectively. However, such multiple signal transmission apparatuses and signal reception apparatuses increase complexity in the hardware configuration.